<!doctype html>
<html lang="zh-CN">
  <head>
    <meta charset="UTF-8" />
    <title>Hulk</title>
    <link rel="stylesheet" href="popup.css" />
  </head>
  <body>
    <div class="container">
      <h1 class="title">改变背景颜色</h1>
      <p class="desc">点击下方按钮将当前页面背景色改为绿色</p>
      <button id="changeColorButton" class="btn">改变颜色</button>
    </div>
    <script src="popup.js"></script>
  </body>
</html>